The Referenced Spectral Ellipsometer (RSE) is a special type of non imaging ellipsometer, whereby the sample is compared to a specifically chosen reference. By that, the ellipsometric difference between sample and reference can be measured. Due to the special optical arrangement, none of the optical components need to be moved or modulated during measurement and the full, high resolution spectrum can be recorded in a single-shot. The device settings are optimized for a specific goal parameter like a small variation of a film thickness prior to a measurement. Due to the differential measurement in combination with this optimization the signal-to-noise ratio is that high, that no averaging is necessary and the full spectral ellipsometric information is acquired within an integration time of 10ms. This way spectral data points are acquired with a data rate of 100 spectra/second. In the present state of the device the information in the spectral range of 450-900 nm is acquired with a spectral resolution of 1.2 nm.

In combination with a synchronized x-y-stage a large-field film-thickness-map of the sample can be measured within a few minutes. Thereby the measurement is done during the movement of the stage. Including acceleration and deceleration times an effective mapping speed of 2 mm²/sec at a spot size of 15x40 µm can be achieved. Additionally the technique is very promising regarding the in situ time dependent changes in thickness.